The present invention relates to an escalator or a moving step assembly.
Escalators and moving step assemblies require a control function and an overwatch or monitoring function in order to ensure the operation thereof as prescribed. In this connection, it is conventionally known to commonly connect a multiplicity of individual sensors and security position switches and display elements, which function as input/output units, to a bus, which, under the control of a so-called bus master, communicates in the respective desired manner with each of the so-connected units.
A bus system of this type has the advantage that individual connections between sensors, on the one hand, and, for example, display elements of the control unit on the other hand, can be dispensed with; a bus cable can be looped through the individual input/output units and can, in this manner, simultaneously provide service of the power supply as well as service of the signal communication between the control unit and the input/output units.
The individual input/output units of an escalator or a moving step assembly have differing criticalities, especially from the perspective of security technology. While, for example, it must be assured in all occurrences, due to the considerable risk of injury, that the drive motor of the escalator is immediately turned off if an escalator guest faces a risk of injury, or if the rate of rotation of the drive motor clearly exceeds the specified rate of rotation, there is no need to implement an operational stoppage, on the other hand, in the event of a partial outage of, for example, a handrail lighting, which has a decorative or aesthetic function.
The ability to automatically overmatch or monitor more and more components of the escalator or moving step assembly is a sought-after objective in the goal of reducing maintenance costs. Thus, for example, data concerning the mass of the extent of a chain hanging between two idler or bogie wheels can be captured as a measure of the wear of the chain and, from this data, the need for a chain exchange can be estimated.
Also, for example, the width of the gap between pallets or steps and the balustrade can be automatically monitored or overmatched. In this connection, the security overwatch points can be combined with aspects of the maintenance function; a security overwatch monitors a gap width for the reason that a maximum value of the gap cannot be exceeded if operational reliability is to be ensured, while, on the other hand, a variation of the gap width beyond a certain measure indicates a wear condition requiring maintenance such as, for example, a maintenance condition with respect to the idler or bogie wheels of the escalator steps.
The more complicated a bus system is, then, correspondingly, the greater is the susceptibility thereof to disturbances, for the reason alone of the correspondingly increased number of connections. However, in order to ensure the required reliability against outage of the operationally necessary units, it has become conventional practice to deploy a special security circuit which constantly overwatches or monitors the functional capability of the security relevant units. A security circuit of this type, however, increases the operational effort considerably so that while the security is, in fact, increased, the downtime of the escalator or the moving step assembly is correspondingly greater.
On the other hand, precisely because of such considerations of security monitoring, there has been a turning away from configuring the connectors of the security circuit as a bus system toward, instead, configuring the connectors of the security circuit to extend to and from the control unit in a star radiating-type configuration, which brings with it a correspondingly high wiring effort.
The present invention provides a solution to the challenge of providing an escalator or moving step assembly which makes possible an improved system availability while, nonetheless, comprising an especially reliable layout of the security function.
The solution provided by the present invention is set forth in the description and patent claims hereof.
In accordance with the present invention, it is particularly advantageous that no modification of the bus system is required but, nonetheless, the security category 4 of the security norm EN954-1 can be attained. In accordance with the present invention, security slaves are provided in this connection which are preferably provided with respective unique code lists. The security slaves are connected to security position switches which open in response to a failure of a unit. Via verification of the acknowledgement signals of the security slaves, the security monitor can establish a unique error identification without necessitating the deployment of a security-oriented master. Also, no deployment is required of so-called secure bus protocols, which are frequently incompatible with the conventional bus protocols and, as well, the effort needed to configure the double bus systems of this type is avoided.
In accordance with the security category 4, the security function continues even upon the occurrence of errors. The errors are recognized and the escalator or moving step assembly can be shut down in a suitable desired manner such as, for example, via interruption of the motor power supply and the actuation of the operating brakes effected by the motor power supply interruption.
In accordance with another embodiment of the invention, it is advantageous if the security circuit is looped through the input/output units in a shorthand manner. Although, to this extent, an electrical separation is created, with this approach, the same cable can be used. The connector of the security circuit can be disposed within the same protective covering as other connectors in the cable or, as desired, can be separately disposed in a separate protective covering within the cable. Via this approach, a security circuit having the required reliability can be configured, whereby solely two additional contacts are required between the holders of the units and the unit itself.
It is particularly advantageous that the units which are not significantly critical to the security function can, despite being without these contacts, also be inserted into corresponding units, whereby there is no need for a complete renovation of the unit but, and this counts as well in connection with a retro-fitting of a security circuit, solely the security related components need be exchanged.
In accordance with the present invention, it is advantageous that the security monitor is maintained free from control signals. The signal functions of the security monitor are performed solely by turning off or shutting down the escalator or the moving step assembly.
It is to be understood, that, as required, an address identification of the security relevant units is possible in a conventional manner via a serial protocol, in order to thereby localize the particular unit which has failed. In an advantageous embodiment, it is provided that solely a defect condition is permitted to be displayed via the security circuit while the actual evaluation which determines the address of the unit is conducted via the system bus. Via this approach, the effort required for the security circuit is considerably reduced while, at the same time, there is no need for a separate protocol.
In accordance with a further, especially advantageous perspective offered by the invention, the control unit, including the bus master and, as well, the alarm switch circuit, can be arranged in a respective input/output region in which the drive motor of the escalator or the moving step assembly need not likewise be located. It is to be understood that it is advantageous to dispose the relay or thyristor for control of the drive motor adjacent these just-noted separate located components and to connect solely the control inputs of these thyristors or relays with the control unit.
Further advantages, details, and features are set forth in the following description of an embodiment of the invention with reference to the figures of the drawings.